The invention relates to a telephone system and more particularly relates to a system for distributing calls from incoming lines among groups of telephone answering consoles of the basis of call holding times.
In many telephone applications, incoming calls are answered from attendant's consoles which perform designated functions. For example, an airline may have designated directory numbers for reservations, rate and schedule information, and general information. A group of telephone answering consoles and attendants generally is provided for each such function.
Prior art systems are known in which incoming calls directed to a specified directory number having a group of associated call answering consoles, are distributed to the consoles as consoles become available. This is sometimes referred to as automatic call distribution. Some prior art systems employ so-called "call-waiting" queues and incoming calls are identified in a queuing register. While an incoming call is waiting, a periodic announcement may be made to the caller requesting that the caller wait for service. A call-waiting queuing register is necessarily limited in size by the number of spaces allocated and when no further spaces are available, a busy tone must be supplied to the calling line. The busy condition or unreasonably long waiting times before a calling customer is served, clearly should be avoided whenever possible as either of these may well result in the loss of a customer or prospect. As a practical matter, however, it will be too expensive to provide a queue which is insufficiently large to accommodate all calls that may occur under peak traffic conditions. Similarly, it is impractical to provide a sufficient number of consoles and console attendants to handle all incoming calls within a prescribed period of time, under peak traffic conditions. It may be anticipated that the demand on the various groups will differ substantially from time to time. Accordingly, it is desirable to be able to transfer some of the incoming traffic from one group of attendant consoles to another group to minimize waiting time and equalize the work load. In one prior art system, a transfer from one console group to another is effected only when all of the circuits associated with the corresponding attendant consoles of one group are fully occupied and the other group has no calls waiting. Such an arrangement, however, has limited application since it is operative to transfer calls under the specific conditions mentioned and does not take into account the length of time that customers are kept waiting.